The present invention relates to a circuit for generating synchronizing signals such as sampling pulses or address signals used when video signals from a plurality of diagnostic apparatus such as CT (computerized tomographic) imaging systems and US (ultrasonographic) imaging systems are recorded in digital image storing apparatus, and more particularly to a synchronizing signal generating circuit for being incorporated in a digital image storing device, wherein when a plurality of video signals composed of different numbers of scanning lines and issued from imaging devices (such as television cameras) of different types of various diagnostic apparatus are cnverted from analog to digital signals and stored in an image memory in the digital image storing apparatus, sampling pulses synchronous with the horizontal synchronizing signals of the video signals and field discriminating signals are generated by using an N-multiplying circuit controlled by a frequency-to-voltage (F/V) converter and a field discriminating circuit controlled by the F/V converter, and the video signals are recorded orderly per frame in the image memory on a real-time basis by utilizing the sampling pulses and the field discriminating signal.
Images thus stored may be employed in signal sources for various image recording apparatus such as multiformat cameras, laser printers, thermal printers, ink jet printers, and the like, in input sources for simple PACSs (picture achieving and communication systems) as analog sources, in primary image storage systems for X-ray television or cinematographic systems, and in image buffers to which the principles of image memories are applied or scan converters, etc.
Continuous image information obtained by CT, US or the like of an affected part of a human body and a surrounding area, for example, is very useful to doctors since it gives visual indications of the affected part and its surrounding area. If a plurality of pieces of such image information are recorded on photographic films, for example, for use as hard copies, then they can readily be used for medical diagnosis without time and space limitations.
However, video signals produced by the various medical image diagnostic apparatus of the type referred to above may not necessarily be of identical specifications or formats, but are likely to differ from diagnostic apparatus to diagnostic apparatus with regard to the number of scanning lines, field frequencies, and other aspects.
In order to store video images composed of different numbers of scanning lines in the image memory of a digital image storing apparatus, it has been necessary to employ a sampling signal generating circuit for generating a number of sampling signals suited to and synchronous with respective numbers of scanning lines and a plurality of image storing apparatus each having constants set for one of the video signals.
With the recent technical advance of medical diagnostic apparatus, there have been proposed many types of such medical diagnostic apparatus including, in addition to CT and US, DF (digital fluorographic) apparatus, MRI (magnetic resonance imaging) apparatus, RI (radioisotope) apparatus, and others. Therefore, if independent digital image storing apparatus designed for use respectively with these medical diagnostic apparatus were employed, the entire system would highly be costly and require a large installation space.